Hybrids Are the Future, Even on Titan

Of all the planets and moons we’ve landed on, Titan might be the coolest.

The Huygens probe landed on the Saturnian moon in January 2005, sending back yellow-tinged pictures of weathered rocks from its landing point before falling silent. And while one view is all we saw--Huygens couldn’t move--it was enough to make scientists want more. The moon, with its mountains and ethane and methane seas that cycle around the body like water does on Earth, is the closest analogue to our planet in the solar system. Who wouldn’t want to go look around?

Exploring Titan, like most places, is easier said than done. It’s hard to get around those mountains and lakes that make the moon so Earth-like. There have been a number of equally plausible spacecraft proposed--rovers, boats, gliders, even hot air balloons--but they’re all limited in their applications. A rover can’t swim and a boat can’t fly. But what if there was a spacecraft that could do everything from, say, roving the surface to flying over tough spots? As it turn's out, that’s just what a team of engineers from the Robotics Lab at Illinois Institute of Technology have come up with.

Arash Kalantari and Matthew Spenko have conceived a brilliant design: the HyTAQ Robot (Hybrid Terrestrial and Aerial Quadrotor). It’s a novel design in that it's basically a cage that can both roll and fly.

It all comes down to the quadrotor configuration that sits inside the cage. These four mini-rotors provide enough lift and thrust for the cage to fly. On the ground, the same actuators give the momentum that the cage needs to roll along the surface. Keeping the system simple with one set of mechanisms helps keep the overall weight down, making it particularly suited for exploring other worlds.

It’s sort of a brilliant design. The robot’s cage is a lightweight frame, allowing it to cross Titan’s frozen and sometimes slushy terrain with ease. If the robot does get stuck or come up to something too big to rove over or around, it can fire up with blades and fly right over it. The cage is also less likely to get stuck than a traditional rover wheel. But that’s not the design's only selling point. By combining two types of robots, the IIT team has given their hybrid a longer lifetime.

Traditional aerial quadrotors typically have a very short operational lifetime. Adding a rolling component lessens the energy demand on the robot. The power this hybrid needs to overcome rolling resistance is relatively little compared to the power it needs to fly. On the while, this design is expected to travel four times further and six times longer than a comparable flying-only design. This longer life would definitely come in handy when you’re roaming around millions of miles from the nearest outlet to recharge your batteries.

Unfortunately for those Titan-lovers among us, this hybrid rover is still just a concept. Neither NASA nor the European Space Agency – the two agencies that joined forces on the Cassini-Huygens mission – have contracted IIT to actually build a flight version of the HyTAQ Robot. But maybe the idea’s general awesomeness will draw the attention of the private sector. Here's hoping some Texan with oil money to spare, or Elon Musk, will turn away from Mars for a minute and take up the challenge of exploring Titan with this innovative, and totally awesome, hybrid rover.